Change Of Crustal Stress Caused By Mining And The Possible Failure Modes In Pillar Recovery

Rock burst is a kind of sudden happening geological hazard that makes great damage in mining process. With the mining depth increasing, rock burst hazard will become more significant and prominent. This article has two parts. First, on the basis of comprehensively analyzing the mining history and its stability, this work established a three-dimensional ANSYS finite element model and simulated the large areas continuous mining process of the lean ore of the upper plate. The results of the simulation include the stress, strain and the stability of the safety pillar. Compared with the results of previous works, we find that the influence of the lean ore mining is much more obvious compared with the mining of the rich ore. During the mining process, stress concentration in the safety pillar is becoming more and more serious, and threatens the security of the open pit slope. Using adaptable strength theories on the simulation results, we evaluate the security of the safety pillar and get conclusions being consistent with the practical conditions. Second, inspired by the press model of rock samples, we proposed two models to determine the instability conditions of a pressed ore pillar through a series of simplifications. Then apply the models established to analyze instability incidents in the practical engineering and point out reasons for the instability. At last, several comments and suggestions are proposed to lower the rate of accidents and optimize the mining program.